Food container

ABSTRACT

A food container formed by compressing a mixed material composed of unboiled bamboo fibers and mixed fibers prepared by mixing unboiled grass family vegetable fibers and unboiled legume family vegetable fibers such as lespedeza fibers. A food container formed by compressing a mixed material composed of the above mixed material, a small amount of water repellent, and a small amount of paper strength additive.

INDUSTRIAL FIELD OF THE INVENTION

The present invention relates to a food container that is mainlycom-posed of nonwoody fibers such that whether used as a packagingmaterial for foods or used as a tableware it will be protected well fromgetting mildewed, and it may be discarded without causing anyenvironmental pol-lution.

PRIOR ART

As known widely, the prior art food packaging containers and throw-awaytableware such as trays, cups, bowls or else have usually beenfoam-molded using a sheet of any proper resin, for example a polystyreneresin. Some coffee cups and the like tableware have however been made bymolding into a shape certain paper sheets each laminated with asynthetic resin sheet.

The prior art food containers formed of those materials are neitherdisinfectant nor mildewproof. If any raw or unheated food like a dailydish is packaged in these containers, then it will spoil or get mildewedsoon, becoming unmarketable. Three kinds of mildews that are blue molds,black molds and black Cladosporium cladosporioides are so active andhardy that it has been difficult to prevent them from growing. In a casewherein laminated paper sheets are used to form food containers, a mainmaterial thereof is a woody pulp. Woody pulps have adversely caused notonly over-deforestation but also needed vast consumption of chemicals.Used food containers of this type may be buried in earth for example atany reclamation site, but they will never completely decay for a longtime. If alternatively such used containers are burned, then producetoxic gases causing environmental disruption or pollution. Thus, therehas been a strong demand for development of a novel type food containerfree from these problems.

DISCLOSURE OF THE INVENTION

The present invention was made to resolve the described drawbacks thathad been observed in the packaging, protection and preservation of foodsheld in or on the prior art containers. An object of the presentinvention is therefore to provide a food container that can bemass-produced using inexpensive plant materials and/or certain rawmaterials which had not been utilized on a large scale. The present foodcontainer now ren-dered inexpensive, tough and stout has to be hygienicand harmless enough to protect foods from deterioration and damage thatwould otherwise be caused by various bacteria and mildews. This foodcontainer may also be disposed and left in earth to be ready forbiodegradation, or alternatively burned without emitting any toxicsubstances.

According to the present invention, a food container is an articlemolded by compressing a composition that comprises a non-boiled bamboofiber blended with a non-boiled mixture of Gramineae plant fibers (otherthan bamboo fibers) and Leguminosae plant fibers such as Lespedezafibers. The composition may further contain noticeable amounts of awater repel-lent and a paper-reinforcing agent so as to form a mixturefrom which the container is molded.

In some preferable embodiments, one of the ingredients of thecom-position just noted above may be about 7-50% by weight of ananti-bacterial bamboo fiber originating from bamboo trunks, undergroundstems, skins and/or cores. The other ingredient may be about 50-93 byweight of a boiled mixture of Gramineae plant fiber such as a reed fiberand a Lespedeza fiber, wherein these two fibers are contained generallyat a ratio of 1:1. The composition may be molded into a shape at atemperature of 180° C. or higher, preferably about 200° C., under apressure of about 3 kg/cm² for about 25 sec. Any binders such as thoseused in the ordinary paper making process need not be added herein tosaid composition, because hydrogen bonds appearing between the fiberswill firmly consolidate them together to give the container a desiredshape. Higher contents of the bamboo fiber will make stronger the foodcontainer, but its content at about 30% by weight is preferable in mostcases. In a case wherein the con-tainer is intended for use withrelatively dry foods such as nuts, dry confectionery or the like, thecomposition discussed above in this paragraph may suffice well as it is.If however wet foods are packed in or a cold or hot water is poured inthe container, then small amounts (for example 3-5% by weight) of awater repellent and a paper-reinforcing agent may be blended with thecomposition. Silicone resins and rosin derivatives may be preferred asthe repellent, and polyacrylamide resins may be used as thewaterproofing and reinforcing agent.

As summarized above, the present food container may be manu-factured bythermally and directly compressing in a desired mold cavity thecomposition that comprises the bamboo fiber and the boiled fibermixture. Alternatively, the composition may be dispersed in water toform a slurry subsequently screened to give a web. This web will then bepressed into a desired shape. Raw bamboo fibers contained in saidcomposition are of an antibacterial and mildewproof property. Even ifspores of any bacteria and/or other spores of mildews will possiblydeposit on food from ambient air or occasionally stick to food from anyforeign material, the bamboo fibers would inhibit them from germinatingand growing to spoil or damage the food.

Moisture content in the material of the present food container is of aself-controllability within a wide range of from about 7% to 25%. Withambient humidity getting abnormally high, the material of container willabsorb a considerable amount of vapor so as to lower the internalhumidity of the container. If contrarily the internal humidity hasbecome too low to keep the food in normal state, the material ofcontainer will automatically release the vapor that has been absorbedtherein, thus maintaining the normal condition of food. The foodcontainer does not only withstand any temporary overdrying of ambientair, but also protect well the food from getting overwetted.

The food container molded in the described manner may be used to packagefishes, meat pieces, other fresh foods, dry provisions, lunches or thelike fast food. This container may also be a disposable tableware suchas a cup for precooked Chinese noodles, a coffee cup, a container orbowl for Japanese noodles, rice-based dishes or the like.

Raw materials that have been discarded uselessly are now utilized toproduce the present food container, thereby diminishing material costand lowering manufacture cost. When dumping any used food containers,they may be combusted at such a low temperature that a burner or furnaceis not damaged, never generating any amount of dioxines. If the usedcontainers are thrown away into earth, then underground bacteria andenzymes will function for biodegradation of those containers. A kind offertilizer as a resultant degradation product will improve soilcondition, beneficially to environmental hygiene.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a food container provided in a firstembodiment of the invention;

FIG. 2 is a perspective view of the food container provided in a secondembodiment;

FIG. 3 is a longitudinal cross section of the food container of thesecond embodiment shown in use; and

FIG. 4 is a perspective view of the food container provided in a thirdembodiment.

BEST MODES OF CARRYING OUT THE INVENTION

Now, a first embodiment of the present invention will be describedreferring to FIG. 1. A tray-shaped container of this embodiment isadapted for use to package a relatively dry food. A composition forforming this container comprises 20% of a bamboo fiber, 40% of a reedfiber and 40% of a Lespedeza bicolor fiber, mixed with each other. Thiscomposition was compressed and molded into a shape at a temperature of200° C., under a pressure of 3 kg/cm² for 24 sec. Hydrogen bondsappearing between the fibers did consolidate them together to give thecontainer a shape of tray. In the manufacturing process, a sheet of sucha composition was roughly molded at first to have a rim surrounded by aflash. Then, a second step of finishing the container was carried out toremove the flash from the rim, thereby providing a finished tray asshown in FIG. 1.

In a second embodiment illustrated in FIGS. 2 and 3, another tray isprovided for use with a relatively wet food such as any pieces of meat.A composition for forming this container comprises 20% of a bamboofiber, 40% of a reed fiber and 40% of a Lespedeza bicolor fiber, mixedwith each other. Blended with this composition is 2% of a polyacrylamideas a waterproofing and reinforcing agent, thus giving a finishedmixture. This mixture also was molded into a shape at 200° C., under 3kg/cm² for 24 sec. Hydrogen bonds appearing between the fibers didconsolidate them together firmly to make the container maintain a shapeof tray. Also, a two-step process was employed in manufacture of thetray of this embodiment. FIG. 2 shows the food container empty but readyto use, with FIG. 3 illustrating it in use. Although not shown in thedrawings, the described mixture may be used to mold similarly to secondembodiment another container that is of a different shape to packcertain precooked lunches.

Now, FIG. 4 is referred to for description of a third embodiment, inwhich a disposable coffee cup is manufactured for use with an automaticvending machine. A composition for forming this container comprises 30%by weight of a bamboo fiber, 35% by weight of a reed fiber and 35% byweight of a Lespedeza bicolor fiber, mixed with each other. Blended withthis composition are 2% by weight of a polyacrylamide as awater-proofing and reinforcing agent and 3% by weight of asilicone-based water repellent. Such a mixture was dispersed in water toform a slurry, which was then filtered through a screen to give a wetcubic article. This article was of a configuration corresponding to afinished container, and subse-quently thermally compressed into a shapeat 200° C., under 3 kg/cm² for 24 sec. FIG. 4 shows a resultant coffeecup, the reference symbol ‘C’ de-noting a body thereof. This cup may notnecessarily be used in the vend-ing machine, but alternatively becombined with an amount of coffee beans, a filter and so on to providean assembled and packed coffee set for sale. In this case, the cup mayhave a grip 3 that will be made integral with the body at the finishingstep in manufacture process, as indicated at the phantom lines in FIG.4. It will be apparent that the same mixture as used in this embodimentmay likewise be molded into another container for any noodles, anyprecooked rice-based dishes or the like.

1. A food container molded by compressing a composition that com-prisesa non-boiled bamboo fiber blended with a non-boiled mixture of Gramineaeplant fibers and Leguminosae plant fibers such as Lespedeza fibers.
 2. Afood container molded by compressing a composition that com-prises anon-boiled bamboo fiber blended with a non-boiled mixture of Gramineaeplant fibers and Leguminosae plant fibers such as Lespedeza fibers,wherein the composition further contains noticeable amounts of a waterrepellent and a reinforcing agent.
 3. A food container as defined inclaim 1 or 2, wherein content of the bamboo fiber in the compositiondoes fall within a range from 7% by weight to 50% by weight.
 4. A foodcontainer as defined in claim 1 or 2, wherein ratio by weight of theGramineae plant fibers to the Leguminosae plant fibers is generally 1:1.